Small Animal Dermatology, 3rd edition

46 BASICS

 Special considerations:
Inflammatory cells degenerate with infection but often remain intact with

immune-mediated skin disease

Acantholytic cells may be present in large numbers and lend diagnostic infor-

mation (e.g., pemphigus foliaceus)

Large number of epithelial cells with few bacteria may indicate a keratinization

disorder or hypothyroidism

Keratinocytes may have melanin granules (may be mistaken for bacteria)

Normal cerumen does not take up stain

Neutrophils without bacteria may indicate a hypersensitivity reaction to medi-

cations being placed in the ear canal (e.g., neomycin, propylene glycol).

DIRECT IMPRESSION SMEARS: TOUCH

IMPRINTS/TZANCK PREPARATION

Used to diagnoseMalasseziaovergrowth or to evaluate ulcers and plaques.

 Press a glass slide directly onto the surface of the skin several times in the same site –

often used if the surface of the skin is greasy (Figure 5.8),or

 Press the slide onto a cut surface of a biopsy specimen or directly onto a plaque/

ulcer/erosion (Figure 5.9).

 If obtaining samples from the cut surface of a biopsy specimen, gently blot excess

blood from the surface using a dry gauze sponge prior to making the imprint and air

dry the slide prior to staining.

 Heat-fix samples obtained from a greasy surface prior to staining unless adhesive

slides are used (optional).

 Collect samples for yeast identification by cotton swab or spatula rolled onto the

slide (especially sensitive areas such as the perivulvar and perianal regions), or by

superficial skin scraping spread onto the slide.

 For interdigital lesions, samples may be collected by impression of the interdigital

web directly onto the slide.

 For paronychia, nail bed debris may be obtained by using a tongue depressor or spat-

ula scraping of the region and then spread onto the glass slide.

 Sample crusted lesions and epidermal collarettes by gently removing the surface or

margins of the lesion with a sterile needle and imprinting the subjacent surface on a

glass slide.

 Use the same arbitrary scale for quantification of yeast as used with otic swab.

FINE-NEEDLE ASPIRATION

Used to examine pustules, nodules, and tumors.

 Use a 22 gauge needle with attached 6 cc syringe for nodules/tumors.

 Use a 23 gauge needle with attached 3 cc syringe for smaller lesions (such as

pustules).